Transformer insulation performance test method, circuit, and apparatus

Abstract

The application relates to a transformer insulation performance test method, circuit and device. The method comprises the following steps: acquiring a cutoff frequency of a filter circuit in insulation performance test; when the cutoff frequency is a preset multiple of a test preset frequency, determining a capacitance value of a target capacitor in the filter circuit according to a resistance value of a target resistor in the filter circuit and the test preset frequency; obtaining a target filter circuit according to the target resistor and the target capacitor, and performing transformer insulation performance test according to the target filter circuit. The above method can improve the accuracy of transformer insulation performance detection of a measured sample.

Description

Technical Field

[0001] This application relates to the field of electrical equipment insulation diagnosis technology, and in particular to a method, circuit and device for testing the insulation performance of a transformer. Background Technology

[0002] Transformers, as the core of energy conversion in the process of power transmission and distribution, are key equipment for ensuring the safe operation of the power grid. During long-term use, the moisture content of the oil-paper insulation in transformers may become too high due to the influence of climate factors such as dampness, thereby reducing the insulation performance of the transformer.

[0003] To test the insulation performance of transformers and take timely measures to extend their lifespan and improve operational reliability, it is necessary to accurately assess the moisture content of the oil-paper insulation in transformers. The dielectric response method is a common method for detecting the moisture content of oil-paper insulation by analyzing the response characteristics of the insulating medium under an applied test signal. Because the oil-paper insulation in transformers has a relatively high impedance and a small response current signal, in actual testing, the response current signal is usually amplified by a current amplification unit, then converted into a voltage signal by a filter circuit containing a sampling resistor and a filter capacitor, and finally calculated to obtain the actual response current signal.

[0004] However, during the amplification process of the response current through the current amplification module, there are cases where the current amplitude is too large or too small, resulting in low accuracy of the transformer insulation performance test results. Summary of the Invention

[0005] Therefore, it is necessary to provide a transformer insulation performance testing method, circuit, and device that can improve the accuracy of insulation performance testing in response to the above-mentioned technical problems.

[0006] Firstly, this application provides a method for testing the insulation performance of a transformer. The method includes:

[0007] Obtain the cutoff frequency of the filter circuit in the insulation performance test;

[0008] When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency.

[0009] The target filter circuit is obtained based on the target resistance and target capacitance, and the transformer insulation performance is tested based on the target filter circuit.

[0010] In one embodiment, obtaining the cutoff frequency of the filter circuit in the insulation performance test includes:

[0011] An AC test voltage signal is input to the filter circuit, and the cutoff frequency of the filter circuit in response to the AC test voltage signal is obtained.

[0012] In one embodiment, when the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined based on the resistance value of the target resistor in the filter circuit and the test preset frequency, including:

[0013] The capacitive reactance of the target capacitor is obtained from the resistance value of the target resistor in the filter circuit.

[0014] The capacitance value of the target capacitor is obtained based on the capacitive reactance and the preset test frequency.

[0015] In one embodiment, the resistance value of the target resistor in the filter circuit is obtained in the following way:

[0016] A DC test voltage signal is input to the filter circuit, and the resistance value of the target resistor is obtained based on the DC test voltage signal.

[0017] In one embodiment, the method further includes: when the cutoff frequency is not a preset multiple of the test preset frequency, updating the target resistor in the filter circuit until the cutoff frequency is a preset multiple of the test preset frequency.

[0018] In one embodiment, the transformer insulation performance test is performed based on the target filter circuit, including:

[0019] The response current signal of the target transformer is obtained based on the target filter circuit, and the insulation performance of the target transformer is tested based on the response current signal.

[0020] In one embodiment, the preset multiplier is 18-22 times.

[0021] Secondly, this application also provides a transformer insulation performance testing circuit. The circuit includes a current amplification circuit, a target filter circuit, and a data analysis circuit connected in sequence.

[0022] A current amplifier circuit is used to amplify the response current during transformer insulation performance testing.

[0023] The target filter circuit is used to collect and filter the current output from the current amplifier circuit, and then output it to the data analysis circuit for analysis.

[0024] Data analysis circuit, used to test the insulation performance of transformers based on the target filter circuit;

[0025] The target filter circuit is obtained in the following way:

[0026] Obtain the cutoff frequency of the filter circuit in the insulation performance test; when the cutoff frequency is a preset multiple of the preset test frequency, determine the capacitance value of the target capacitor in the filter circuit based on the resistance value of the target resistor in the filter circuit and the preset test frequency; obtain the target filter circuit based on the target resistor and the target capacitance.

[0027] In one embodiment, the target filter circuit includes a target capacitor and a target resistor connected in parallel; the parallel target capacitor or target resistor is connected in parallel with the current amplifier circuit.

[0028] Thirdly, this application also provides a transformer insulation performance testing device. This transformer insulation performance testing device is used to perform the following steps:

[0029] Obtain the cutoff frequency of the filter circuit in the insulation performance test;

[0030] When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency.

[0031] The target filter circuit is obtained based on the target resistance and target capacitance, and the transformer insulation performance is tested based on the target filter circuit.

[0032] Fourthly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0033] Obtain the cutoff frequency of the filter circuit in the insulation performance test;

[0034] When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency.

[0035] The target filter circuit is obtained based on the target resistance and target capacitance, and the transformer insulation performance is tested based on the target filter circuit.

[0036] Fifthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0037] Obtain the cutoff frequency of the filter circuit in the insulation performance test;

[0038] When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency.

[0039] The target filter circuit is obtained based on the target resistance and target capacitance, and the transformer insulation performance is tested based on the target filter circuit.

[0040] Sixthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0041] Obtain the cutoff frequency of the filter circuit in the insulation performance test;

[0042] When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency.

[0043] The target filter circuit is obtained based on the target resistance and target capacitance, and the transformer insulation performance is tested based on the target filter circuit.

[0044] The aforementioned transformer insulation performance testing method, circuit, and apparatus obtain the cutoff frequency of the filter circuit in the insulation performance test. When the cutoff frequency is a preset multiple of the preset test frequency, the capacitance value of the target capacitor in the filter circuit is determined based on the resistance value of the target resistor in the filter circuit and the preset test frequency. The target filter circuit is then obtained based on the target resistance and target capacitance, and the transformer insulation performance is tested based on the target filter circuit. Currently, in dielectric response insulation performance testing, the response current signal of the transformer under test is amplified to assess the moisture content of the oil-paper insulation. However, during the amplification process, the current amplitude may be too large, exceeding the signal acquisition range; conversely, the current amplitude may be too small, leading to waveform distortion, ultimately resulting in the system being unable to obtain accurate test results. This application embodiment acquires and filters the amplified response current signal through a filter circuit. The target resistor in the filter circuit is used to convert the amplified response current signal into a voltage signal, and the actual response current waveform can be obtained through conversion. By selecting a suitable target resistor, the cutoff frequency of the filter circuit is made to be a preset multiple of the preset test frequency. This ensures that the amplitude of the response current signal or waveform acquired by the sampling resistor in the filter circuit is within a reasonable range. Since the addition of a sampling resistor to acquire the response current will affect the phase difference between the excitation voltage and the response current of the tested sample, i.e., the transformer, a filter capacitor is matched according to the value of the target resistor to compensate the circuit after the addition of the sampling resistor. This restores the original waveform and has a good signal-to-noise ratio, improving the accuracy of the test of the transformer insulation performance of the tested sample. Attached Figure Description

[0045] Figure 1 This is a flowchart illustrating a transformer insulation performance testing method in one embodiment;

[0046] Figure 2This is a schematic diagram of the equivalent filter circuit of the transformer of the sample under test in one embodiment;

[0047] Figure 3 This is a flowchart illustrating the steps for determining the capacitance value of the target capacitor in a filter circuit in one embodiment.

[0048] Figure 4 This is a flowchart illustrating a transformer insulation performance testing method in another embodiment;

[0049] Figure 5 This is a waveform of the response current of the transformer of the sample under test when the target resistance is large in one embodiment;

[0050] Figure 6 The waveform of the transformer response of the sample under test when the target resistance is small is shown in another embodiment.

[0051] Figure 7 This is a waveform of the response current of the transformer of the tested sample when the target resistance is appropriate in one embodiment.

[0052] Figure 8 This is a transformer insulation performance test circuit in one embodiment;

[0053] Figure 9 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0055] In one embodiment, such as Figure 1 As shown, a method for testing the insulation performance of a transformer is provided. This embodiment illustrates the application of this method to a power grid system server. It is understood that this method can be applied to a server, or to a system including both a terminal and a server, and is implemented through interaction between the terminal and the server. In this embodiment, the method includes the following steps:

[0056] Step 102: Obtain the cutoff frequency of the filter circuit in the insulation performance test.

[0057] Among them, insulation performance testing refers to testing the insulation performance of transformers using the dielectric response method. During transformer operation, the insulation material gradually ages due to long-term exposure to temperature, moisture, electric field, and oxygen. Under the influence of an electric field, energy loss occurs within the insulation material due to the hysteresis effect of dielectric conductivity and dielectric polarization.

[0058] Dielectric response method refers to measuring the dielectric relaxation characteristics of an insulating medium under DC or sinusoidal AC voltage to obtain information about insulation aging, moisture absorption, etc., and thus predict the insulation lifetime. Currently, widely used dielectric response measurement methods include time-domain polarization-depolarization current (PDC) and return voltage method (RVM), and frequency-domain dielectric spectroscopy (FDS). Due to its advantages such as convenient field measurement, low susceptibility to environmental interference, rich insulation information, and good interpretability, the dielectric response method is one of the most promising non-destructive testing methods for transformer insulation condition assessment.

[0059] Because the insulation sample has a very high impedance, the response current signal is extremely small, making it impossible for the acquisition circuit to directly identify it. Therefore, in traditional techniques, the response current signal is connected to a current amplification module to amplify the response current passing through the oil-paper insulation, facilitating the assessment of the moisture content of the oil-paper insulation. However, during the amplification process, the response current amplitude may be too large, exceeding the signal acquisition range; or the current amplitude may be too small, leading to waveform distortion, ultimately resulting in the system being unable to obtain accurate test results.

[0060] Based on this, the embodiments of this application adjust the resistance value of the sampling resistor in the filter circuit so that the amplitude of the response current signal or waveform acquired by the sampling resistor in the filter circuit after the response current signal is amplified is within a reasonable range and has a good signal-to-noise ratio.

[0061] The filtering circuit may include reactive components, such as a capacitor connected in parallel across the load resistor. Exemplarily, the filtering circuit includes a sampling resistor and a filtering capacitor connected in parallel. The sampling resistor converts the amplified response current signal into a voltage signal, from which the actual response current waveform can be obtained. Since adding a sampling resistor to acquire the response current affects the phase difference between the excitation voltage and response current of the tested sample (i.e., the transformer), it is necessary to match the filtering capacitor according to the value of the sampling resistor to compensate for the circuit after adding the sampling resistor and restore the original waveform.

[0062] To select a suitable target resistor, the cutoff frequency of the filter circuit can be used as a criterion. In this embodiment, the target resistor is the sampling resistor in the filter circuit whose value needs to be adjusted or selected appropriately. The cutoff frequency is an indicator describing filter performance; it represents the boundary frequency at which the output signal energy of a system begins to decrease significantly or, in a band-stop filter, increases significantly (generally defined as -3dB). To ensure that the amplitude of the acquired response current signal or waveform is within a reasonable range and has a good signal-to-noise ratio, different amplification factors and filter circuits need to be selected for test signals of different amplitudes or frequencies. Based on the amplification of the response current, suitable sampling resistors and filter capacitors are selected as the target resistor and target capacitor to achieve switching between the current amplification factor and the filter cutoff frequency.

[0063] Step 104: When the cutoff frequency is a preset multiple of the test preset frequency, determine the capacitance value of the target capacitor in the filter circuit based on the resistance value of the target resistor in the filter circuit and the test preset frequency.

[0064] The preset test frequency refers to the pre-set frequency of the test signal, which is a variety of electrical signals input into a circuit to observe its characteristics. For example, a signal generator can be used to send a test signal to the transformer under test.

[0065] The cutoff frequency of the filter circuit varies depending on the amplitude and frequency of the test signal. In this embodiment, the amplitude and frequency of the test signal are preset, and the transformer under test is input according to the preset amplitude and frequency to obtain the cutoff frequency of the filter circuit under that test signal.

[0066] For example, after obtaining the cutoff frequency of the filter circuit in the insulation performance test, it is determined whether the cutoff frequency is a preset multiple of the test preset frequency. When the cutoff frequency is a preset multiple of the test preset frequency, it is determined that the response current signal or waveform amplitude acquired by the target resistor with the current resistance value is within a reasonable range and has a good signal-to-noise ratio.

[0067] After determining the target resistor, the capacitance value of the target capacitor in the filter circuit is determined based on the resistance value of the target resistor and the preset test frequency. Since adding a sampling resistor to collect the response current will affect the phase difference between the excitation voltage and response current of the tested sample, i.e., the transformer, it is necessary to match the filter capacitor according to the resistance value of the sampling resistor, compensate for the circuit after adding the sampling resistor, and restore the original waveform.

[0068] Step 106: Obtain the target filter circuit based on the target resistance and target capacitance, and perform transformer insulation performance test based on the target filter circuit.

[0069] In this process, based on the preset test frequency, a target resistor with different resistance values ​​is used as the sampling resistor by adjusting or selecting the target resistor. Then, a suitable target capacitor can be obtained based on the preset test frequency and the target resistor. The target filter circuit is obtained through the target resistor and the target capacitor, ensuring that the cutoff frequency of the target filter circuit is within a suitable range.

[0070] For example, after determining the target filter circuit, the amplified response current is acquired through the target filter circuit and converted into a voltage signal. The actual response current signal can then be obtained through calculation. Based on the actual response current signal and the test signal, the insulation performance of the transformer under test is tested. For instance, the phase difference between the actual response current signal and the test signal can be obtained to determine the dielectric loss of the oil-paper insulation in the transformer under test. The moisture content of the grease insulation can then be determined through the dielectric loss, thereby testing the insulation performance of the transformer under test.

[0071] In the aforementioned transformer insulation performance testing method, the cutoff frequency of the filter circuit in the insulation performance test is obtained. When the cutoff frequency is a preset multiple of the preset test frequency, the capacitance value of the target capacitor in the filter circuit is determined based on the resistance value of the target resistor in the filter circuit and the preset test frequency. The target filter circuit is then obtained based on the target resistance and target capacitance, and the transformer insulation performance is tested based on the target filter circuit. Currently, in dielectric response insulation performance testing, the response current signal of the transformer under test is amplified to assess the moisture content of the oil-paper insulation. However, during the amplification process, the current amplitude may be too large, exceeding the signal acquisition range; conversely, the current amplitude may be too small, leading to waveform distortion, ultimately resulting in the system being unable to obtain accurate test results. This application embodiment acquires and filters the amplified response current signal through a filter circuit. The target resistor in the filter circuit is used to convert the amplified response current signal into a voltage signal, and the actual response current waveform can be obtained through conversion. By selecting a suitable target resistor, the cutoff frequency of the filter circuit is made to be a preset multiple of the preset test frequency. This ensures that the amplitude of the response current signal or waveform acquired by the sampling resistor in the filter circuit is within a reasonable range. Since the addition of a sampling resistor to acquire the response current will affect the phase difference between the excitation voltage and the response current of the tested sample, i.e., the transformer, a filter capacitor is matched according to the value of the sampling resistor to compensate the circuit after the addition of the sampling resistor. This restores the original waveform and has a good signal-to-noise ratio, thereby improving the accuracy of the insulation performance test of the tested sample transformer.

[0072] In one embodiment, when the cutoff frequency is a preset multiple of the test preset frequency, in the process of determining the capacitance value of the target capacitor in the filter circuit based on the resistance value of the target resistor in the filter circuit and the test preset frequency, the preset multiple can be selected as 18 to 22 times. Preferably, when the cutoff frequency is 20 times the test preset frequency, a smoother sinusoidal current waveform can be obtained.

[0073] This embodiment sets a preset multiple range, that is, when the cutoff frequency is 18 to 22 times the preset test frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the preset test frequency, so that the obtained response signal of the transformer under test is a relatively smooth sinusoidal current waveform, thereby having a good signal-to-noise ratio and improving the accuracy of insulation performance testing of the transformer under test.

[0074] In one embodiment, the step of obtaining the cutoff frequency of the filter circuit in the insulation performance test includes: inputting an AC test voltage signal to the filter circuit and obtaining the cutoff frequency of the filter circuit in response to the AC test voltage signal.

[0075] See Figure 2 , Figure 2 The diagram shows an equivalent filter circuit of the transformer of the sample under test in one embodiment. The filter circuit can be equivalent to a parallel model of the target resistor R and the target capacitor C.

[0076] In one implementation, the target resistor R and the target capacitor C are connected in parallel to form a first node and a second node. Applying an AC test voltage signal to the filter circuit can apply an AC voltage with a preset test frequency f between the first node and the second node.

[0077] This embodiment obtains the cutoff frequency of the filter circuit in response to the AC test voltage signal by inputting an AC test voltage signal into the filter circuit, and can select a suitable target resistor by using the cutoff frequency.

[0078] In one embodiment, such as Figure 3 As shown, when the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined based on the resistance value of the target resistor in the filter circuit and the test preset frequency, including:

[0079] Step 302: Obtain the capacitive reactance of the target capacitor based on the resistance value of the target resistor in the filter circuit.

[0080] For example, when applying an AC test voltage signal to the filter circuit, such as Figure 2 As shown, the capacitive reactance at the preset test frequency can be calculated based on the resistance value of the target resistor R, and the equivalent capacitance value of the target capacitor C can be calculated from the capacitive reactance.

[0081] Step 304: Obtain the capacitance value of the target capacitor based on the capacitive reactance and the preset test frequency.

[0082] The capacitance value of the target capacitor C can be calculated using the following formula:

[0083]

[0084] Where Z represents impedance, ω represents angular frequency, f represents the preset test frequency, and C represents the capacitance value of the target capacitor.

[0085] In this embodiment, when the cutoff frequency is a preset multiple of the test preset frequency, the capacitive reactance of the target capacitor is obtained based on the resistance value of the target resistor in the filter circuit. The capacitance value of the target capacitor is obtained based on the capacitive reactance and the test preset frequency. After determining the selection of the target resistor based on the cutoff frequency of the filter circuit, since the addition of a sampling resistor to collect the response current will affect the phase difference between the excitation voltage and response current of the tested sample, i.e., the transformer, the filter capacitor is matched according to the resistance value of the sampling resistor to compensate the circuit after the addition of the sampling resistor, restore the original waveform and have a good signal-to-noise ratio, thereby improving the accuracy of the test of the insulation performance of the tested sample transformer.

[0086] In one embodiment, the resistance value of the target resistor in the filter circuit is obtained by inputting a DC test voltage signal to the filter circuit and obtaining the resistance value of the target resistor based on the DC test voltage signal.

[0087] See Figure 2 When applying a DC voltage to the filter circuit, for example, Figure 2 The voltage in the circuit is set to DC voltage. At this time, the target capacitor is equivalent to a short circuit. The resistance value of the target resistor R can be calculated by Ohm's law. The resistance value of the target resistor R is its actual resistance value in the insulation performance test circuit.

[0088] In one implementation, the target capacitor C and the target resistor R are connected in parallel to form a first node and a second node, and the DC voltage applied to the filter circuit can be applied between the first node and the second node.

[0089] This embodiment inputs a DC test voltage signal to the filter circuit and obtains the resistance value of the target resistor based on the DC test voltage signal. After selecting the target resistor, the actual resistance value of the target resistor in the insulation performance test circuit can be obtained, and the capacitance value of the target capacitor can be further determined based on the resistance value of the target resistor.

[0090] In one embodiment, the transformer insulation performance testing method further includes: when the cutoff frequency is not a preset multiple of the test preset frequency, updating the target resistor in the filter circuit until the cutoff frequency is a preset multiple of the test preset frequency.

[0091] If the cutoff frequency is not a preset multiple of the test preset frequency, the resistance value of the sampling resistor is adjusted until the cutoff frequency is a preset multiple of the test frequency. Then, the sampling resistor with the current resistance value is determined as the target resistor, and the capacitance value is recalculated based on the current target resistor value, thereby selecting the target capacitor corresponding to the capacitance value.

[0092] In this embodiment, when the cutoff frequency is not a preset multiple of the test preset frequency, the target resistor in the filter circuit is updated until the cutoff frequency is a preset multiple of the test preset frequency. By adjusting the range of the target resistor in the filter circuit, a suitable target resistor is obtained so that the cutoff frequency of the filter circuit is a preset multiple of the test preset frequency, thereby enabling the filter circuit to obtain a response current with reasonable amplitude and good signal-to-noise ratio.

[0093] In one embodiment, testing the insulation performance of a transformer based on a target filtering circuit includes: acquiring the response current signal of the target transformer based on the target filtering circuit, and testing the insulation performance of the target transformer based on the response current signal.

[0094] For example, a response current signal with a waveform amplitude within a reasonable range and a good signal-to-noise ratio can be obtained through a target filtering circuit. Based on the response current signal and the test signal, the insulation performance of the transformer under test can be tested. For example, the phase difference between the actual response current signal and the test signal can be obtained to determine the dielectric loss of the oil-paper insulation in the transformer under test. Then, the moisture content of the grease insulation can be determined through the dielectric loss, thereby testing the insulation performance of the transformer under test.

[0095] This embodiment acquires the response current signal of the target transformer through a target filter circuit and tests the insulation performance of the target transformer based on the response current signal. This allows the cutoff frequency of the filter circuit output of the sample voltage under test to be controlled within a preset multiple of the preset test frequency. As a result, when testing the response current of the sample voltage under test based on the dielectric response method, the response current waveform will not exceed the signal acquisition range due to being too large, nor will the output waveform be distorted due to being too small. This improves the accuracy of the insulation performance test of the sample voltage under test.

[0096] In one embodiment, such as Figure 4 As shown, the transformer insulation performance test method includes:

[0097] Step 402: Obtain the cutoff frequency of the filter circuit in response to the AC test voltage during the insulation performance test.

[0098] Step 404: Determine whether the cutoff frequency is a preset multiple of the test preset frequency.

[0099] Step 406: If the cutoff frequency is a preset multiple of the preset test frequency, then obtain the resistance value of the target resistor, and determine the capacitance value of the target capacitor in the filter circuit based on the resistance value of the target resistor and the preset frequency.

[0100] The resistance value of the target resistor is obtained by inputting a DC test voltage signal to the filter circuit and then obtaining the resistance value of the target resistor based on the DC test voltage signal.

[0101] Step 408: If the cutoff frequency is not a preset multiple of the test preset frequency, adjust the target resistor and reacquire the cutoff frequency until the cutoff frequency is a preset multiple of the test preset frequency.

[0102] After adjusting the target resistor so that the cutoff frequency is a preset multiple of the preset test frequency, referring to step 406, a DC test voltage signal is input to the filter circuit, the resistance value of the target resistor is obtained based on the DC test voltage signal, and the capacitance value of the target capacitor in the filter circuit is determined based on the resistance value of the target resistor and the preset frequency.

[0103] Step 410: Obtain the target filter circuit based on the target resistance and target capacitance, acquire the response current signal of the target transformer based on the target filter circuit, and test the insulation performance of the target transformer through the response current signal.

[0104] This embodiment selects a target resistor and a suitable target capacitor with appropriate resistance values ​​in the dielectric response test, so that the cutoff frequency of the filter circuit output can be controlled within a preset multiple of the test frequency. This ensures that when testing the response current of the transformer under test based on the dielectric response method, the response current waveform will not exceed the signal acquisition range due to being too large, nor will the output waveform be distorted due to being too small. This can improve the testing accuracy of the dielectric response equipment.

[0105] Figure 5 The image shows the response current waveform of the transformer under test when the target resistance is relatively large in one embodiment. When the selected target resistance is large, the response current waveform of the transformer under test is as follows: Figure 5 As shown, the sinusoidal response current waveform exhibits a sawtooth pattern, indicating that the current waveform contains a lot of high-frequency noise, which reduces the accuracy of insulation performance testing.

[0106] Figure 6 This is a waveform diagram of the response current of the transformer under test when the target resistance is small, as shown in another embodiment. When the selected target resistance value is small, the response current waveform of the transformer under test is as follows: Figure 6 As shown, the response current waveform is distorted, and the positive and negative high amplitude segments of the sinusoidal current waveform are cut off. This is because the resistance of the target resistor is too small, making it difficult to measure higher currents.

[0107] In this embodiment, based on the determined target resistor value and the preset test frequency, a suitable filter capacitor is selected so that the cutoff frequency of the filter circuit is 20 times the preset test frequency, thus achieving a good filtering effect. Figure 7 The image shows the response current waveform of the transformer under test when the target resistance is appropriate in one embodiment. When the cutoff frequency is 20 times the test frequency, the response current waveform of the transformer under test is as follows: Figure 7 As shown, the response current satisfies a sinusoidal waveform, and the entire waveform is relatively smooth in the time domain, indicating that the range of the target resistor is very reasonable and the waveform value of the actual response current can be read with high precision.

[0108] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0109] Based on the same inventive concept, this application also provides a transformer insulation performance testing circuit. The solution provided by this circuit is similar to the solution described in the above method. Therefore, the specific limitations of one or more transformer insulation performance testing circuit embodiments provided below can be found in the limitations of the transformer insulation performance testing method described above, and will not be repeated here.

[0110] In one embodiment, such as Figure 8 As shown, a transformer insulation performance testing circuit is provided, including a current amplification circuit 804 and a target filter circuit 802 connected in sequence. The current amplification circuit 804 is used to amplify the response current in the transformer insulation performance test, and the target filter circuit 802 is used to collect and filter the current output by the current amplification circuit 804 and output it to the data analysis circuit 806 for analysis. The data analysis circuit 806 is used to perform transformer insulation performance testing according to the target filter circuit.

[0111] The transformer insulation performance test circuit also includes a signal generation circuit 808 and a voltage amplification circuit 810, which are used to apply a test signal of a preset test frequency to the transformer sample under test.

[0112] The target filter circuit 802 includes a target capacitor and a target resistor, which are connected in parallel. The parallel target capacitor or target resistor is then connected in parallel with the current amplifier circuit.

[0113] The target filter circuit 802 is obtained in the following ways: the cutoff frequency of the filter circuit in the insulation performance test is obtained; when the cutoff frequency is a preset multiple of the preset test frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the preset test frequency; the target filter circuit is obtained according to the target resistor and the target capacitor.

[0114] The specific method for obtaining the target filter circuit can be found in the steps outlined in the above embodiment of the transformer insulation performance testing method.

[0115] Based on the same inventive concept, this application also provides a transformer insulation performance testing device, which is used to implement the steps in the above-described transformer insulation performance testing method embodiments.

[0116] Each module in the aforementioned transformer insulation performance testing device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0117] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 9 As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a method for testing the insulation performance of a transformer.

[0118] Those skilled in the art will understand that Figure 9The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0119] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0120] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0121] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0122] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0123] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0124] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method of testing the insulation performance of a transformer, characterized by, The method comprises: According to the pre-set test signal, the measured sample transformer is inputted, and the cut-off frequency of the filter circuit in the insulation performance test is obtained; When the cut-off frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency; the test preset frequency is the frequency of the pre-set test signal; the target resistor in the filter circuit is used to convert the amplified response current signal into a voltage signal, and the actual response current waveform is obtained through conversion; When the cut-off frequency is not a preset multiple of the test preset frequency, the target resistor in the filter circuit is updated until the cut-off frequency is a preset multiple of the test preset frequency; According to the target resistor and the target capacitor, a target filter circuit is obtained, and the transformer insulation performance test is performed according to the target filter circuit; When the cut-off frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency, comprising: According to the resistance value of the target resistor in the filter circuit, the capacitive reactance of the target capacitor is obtained; According to the capacitive reactance and the test preset frequency, the capacitance value of the target capacitor is obtained.

2. The method of claim 1, wherein, The cut-off frequency of the filter circuit in the insulation performance test is obtained, comprising: The cut-off frequency of the filter circuit is obtained by inputting an alternating current test voltage signal to the filter circuit.

3. The method of claim 1, wherein, The resistance value of the target resistor in the filter circuit is obtained by inputting a direct current test voltage signal to the filter circuit. According to the target filter circuit, the response current signal of the target transformer is obtained, and the insulation performance of the target transformer is tested according to the response current signal.

4. The method of claim 1, wherein, The preset multiple is 18-22 times. Comprise the current amplification circuit, the target filter circuit and the data analysis circuit connected in turn; 5. The method of claim 1, wherein, The current amplification circuit is used for amplifying the response current in the transformer insulation performance test; 6. A transformer insulation performance test circuit, characterized by, The target filter circuit is used for collecting and filtering the current output by the current amplification circuit and outputting to the data analysis circuit for analysis; The data analysis circuit is used for testing the transformer insulation performance according to the target filter circuit; The target filter circuit is obtained by the following way: ​ ​ According to a preset test signal, a transformer to be tested is inputted, and a cutoff frequency of a filter circuit in insulation performance testing is obtained; when the cutoff frequency is a preset multiple of a test preset frequency, a capacitance value of a target capacitor in the filter circuit is determined according to a resistance value of a target resistor in the filter circuit and the test preset frequency; the test preset frequency is a frequency of the preset test signal; the target resistor in the filter circuit is used to convert an amplified response current signal into a voltage signal, and an actual response current waveform is obtained through conversion; when the cutoff frequency is not the preset multiple of the test preset frequency, a target resistor in the filter circuit is updated until the cutoff frequency is the preset multiple of the test preset frequency; and the target filter circuit is obtained according to the target resistor and the target capacitor. The method comprises the following steps: According to the resistance value of the target resistor in the filter circuit, a capacitive reactance of the target capacitor is obtained; According to the capacitive reactance and the test preset frequency, the capacitance value of the target capacitor is obtained.

7. The circuit of claim 6, wherein, The target filter circuit comprises the target capacitor and the target resistor, and the target capacitor and the target resistor are connected in parallel; the target capacitor or the target resistor connected in parallel is connected in parallel with the current amplification circuit.

8. A transformer insulation performance testing device, characterized by, The device uses the transformer insulation performance testing method according to any one of claims 1-5.

Images